Plagger – DIY RSS/Atom Aggregation
http://www.plagger.org/

Plagger is a pluggable RSS/Atom feed aggregator written in Perl. Everything is implemented as a small plugin and you can mash them up together using Plagger core API and plugin hooks. You can think of Plagger as a blosxom or qpsmtpd for RSS aggregator. This has been added to the Resource section of Bots, Blogs and News Aggregators.